Method of balancing disturbing forces and couples which are produced in a reciprocating engine



Get. 23, 1923. v v 11,472,6M12

' C. L. A. M. LEBLANC METHOD OF BALANCING DIS-TURBING FORCES AND-COUPLESWHICH ARE PRODUCED IN A RECIPROGATING ENGINE Filed A112. 5. 1921 2Sheets-Sheet 1 IN VE/V 7'01? c t., 23 11923. lA-YZMZ C. L. A. M. LEBLANCMETHOD OF BALANCING DISTURBING FORCES AND COUPLES WHICH ARE PRODUCED INA RECIPROCATING ENGINE Filed Ausz. 5, 1921 2 Bheets-Sheet 2 lltlPatented @ct. 23, I923,

uurrnn stares IAIZIIIZ PATIENT @FFICEO CHARLES LEONARD ARMANI) MAURICELEBLANC, 0115 PARIS, FRANCE, iASSIG-NOR T0 SOCIETE ANONYME POURLEXPLOITATION DES PROCEDE S MAURICE LEBJLANC- VICKERS, 0F PARIS, FRANCE.

METHOD 0E BALANCING DISTURBING FORCES AND COUPLES WHICH ARE PRODUCED INA BECIPROGATING ENGINE.

Application filed August 3, 1921. Serial No. 489,604).

To all whom it may concern:

Be it known that I, CHARLES IntoNAno ARMANI) MAURICE LEBLANo, a citizenof the Republic of France, residing in Paris, France, have invented anImprovement in Methods of Balancing Disturbing Forces and Couples. whichare Produced in a Reciprocating Engine, of which the following is aspecification.

In engines comprising cylinders in which a piston has a reciprocatingmotion converted into rotary motion by a connecting rod and cranksystem, the, several moving parts give rise to periodic inertia forcesand conples. These forces and couples are the cause of disturbingreactions, which affect the bearings of the engine. In the case of motorcars especially these reactions cause vibrations in the springs andunderframe, which it is desirable to reduce to a minimum, and at thesame time they impart insupportable rocking, pitching and zigzagmovements to the car.

The balancing of the inertia forces and couples is effected in practicein several ways: Suitably calculated balance weights may be arranged oncertain of the moving parts; this method gives only very inade quateresults. In motor car construction attempts have been made to combinewith this method the use of multiple driving cylinders acting on thesame driving shaft and suitably arranged with respect to each other.

The present invention has for its object a simple method for balancingin a perfect manner a single cylinder engine and it may be extended toengines with several cylinders.

Fig. 1 is a diagrammatic section of an engine of the single cylindertype through a plane containing the axis Ow of the cylinder and at rightangles to the axis of rotation, which is indicated at 9.

Figs. 2 and '3 are theoretical diagrams. Fig. 4 illustrates one methodof carrying out the balancing system; Fig. 5 is a longitudinal sectionand Fig. 6 a cross section on the line XX of Fi 5, of a two cycle enginewith two cylin ers the piston and connecting rods of which are coupledto the same crank shaft, and to which the balancing system of thepresent invention is applied by making use for this purpose of gearedblowers of the Roots type..

Referring to Fig. 1, P is the piston, AB the connecting rod and A0 thecrank. The reclprocating motions communicated to these moving parts giverise at each instant to inert a forces of which X, Y are the componentson the co-ordinate axes Ow, 01 of the resultant F of these forces.

()n the other hand the oscillatory motion of the connecting rod aroundits centre of gravity gives rise to an inertia couple G, the axle ofwhich is at right angles to the plane of the figure.

The components X, Y of the force F and the couple G are of necessityperiodic time functlons, and it is known that such functions may beexpressed by the sum of sine functions of increasing frequency of theform;

A sin 21: at B sin 41:: at C sin 61*: at etc., in which n is thefrequency of the engine, that is to say the number of revolutions persecond. Theory shows that in the conditions of practice the terms of afrequency higher than that of the engine are generally negligible, andthat X, Y, G,

may be expressed by equations of the form- Xzdn n A sin 21: 'nt Yz lw nB sin 21: 'nt 624m n C sin 21: at

in which the coefiicients A, B, C, depend only on the dimensions, massesand shape of the moving parts.

Whcn an excentric additional mass is keyed on the shaft of the engine,the rotary motion pf this mass produces no couple but gives rise to asupplementary force the components X Y of wh-ichalong the axes Um, 07are two sine functions of frequency N/and of the same amplitude (Fig.2). The mass of this counterweight may be chosen and it may be keyed insuch manner as to balance continuously the force X produced by theengine along the axis of the cylinder; it is seen however, that thecomponent Y which will have been produced simultaneously cannot balancethe com nent Y. With regard to the couple, this W1 1 not have the Bootstype, whic plane of s mmetr y of th that of the cylinder, a secondadditional mass is arranged, and is caused to rotate at the same speedas the first, but in the reverse direct-ion, the rotary motion of thesetWo masses produces forces and a couple, which, provided they aresuitably fixed and dimensioned permits a complete balance of the engineto be attained.

In Fig. 3, let p. be the additional mass fixed on the shaft of theengine at a distance p from the axis U; let p be the second additionalmass rotating around the auxiliary axis at a distance p from th1slatter. Let itbe the distance apart of the two, axes (l, 0 The mass plrotates in the direction of the arrow 1, the mass p? in the direction ofthe arrow 2. The first mass produces the forces X Y acting at (l, thesecond the forces X Y acting at 0'; by fixing p. suitably with respectto 1. it may be arranged that X is continuously directed in the samedirection as X; the component Y will then be continuously directed inthe reverse direction to Y. It is possible to determine p. p and a p insuch manner that the components X+X Y--Y of the forces due to theadditional masses ectively balance at each instant the forces Y.produced by the moving parts of the engine.

On the other hand the rotation of. the additional masses gives rise to acouple 7/ (IF-Y It can be chosen in'such manner that this additionalcouple balances the cou-' ple due to the engine.

It is thus clear that employmg this second additional mass itlispossible to ensure the complete balance of the engine.

The system of balancing can be obtained practically in the followingway:

Two wheels or two trains of gear wheels of the sameradius are fixed.respectively on the shafts 0 and Q; the masses a and pd are respectivelykeyed on each of these wheels, at suitable distances from the axis (Fig.4;).

The desired result can also be obtainedby putting one of the wheels outof balance with the other, for exam le by means of aper= tures suitablymade in one of them.

It is this system which is applied in the engine shown by way ofexamplein Fl 5 and 6.

In this two cycle en ine, two blowers of serve to force air into thecylinders, are located at the two endsof the shaft at equal distancesfrom the at right angles to the shaft. In each ese blowers, the impeller21 keyed on the engine shaft, and consequently rotating in thesame-direction and i at the same speed as this latter, gears with theimpeller 23 keyed on the auxiliary shaft 24 which is parallel to theegine shaft, carried in the same vertical plane and integral with thefixed parts of the frame. The im:

peller 23 is put out of balance by means of an aperture suitablycalculated. The excentric masses 26 carried on the engine shaft serve asthe additional mass p. in the preced-- The impeller The methods ofcarrying out the inven tion hereinabove described are only shown by waof example. The general method which as been described allows ofbalancing the forces and couples of inertia of frequency n, the onlyones which in practice have an important disturbing effect. In the casewhere it is desired to balance also forces and couples of a frequencywhich is a multieof the fundemental frequency 11.; this can u donesimilarly by analogous means. For instance in the case of forces X Y,and a couple G of frequency 2%, it will sufiice to arrange two newadditional masses, one rotating'round the engine shaft and in the samedlrection at twice the speed of the shaft, the other rotating at thesame speed as the shaft but in the opposite direction around anauxiliary shaft parallel therto, and located at a fixed distancetherefrom; this result can be obtained by means of suitably arrangedgearing.

What I claim is 1. In combination with the cylinders and pistons of atwo cycle engine, a crank shaft, separate piston rods between the shaftand the separate pistons, and means for deliverin air under pressure tothe engine and for b ancing the engine, comprising a blower, consistingof a casing located on the frame of the engine and communicating with acylinder of the engine, a. balanced impeller mounted on said crankshaft, and located in said casing, an unbalanced impeller located withinsaid casing and cooperating with the balanced impeller, a shaft on whichthe unbalanced impeller is mounted, located eccen.

trically of saidcrank shaft and spaced a predetermined distancetherefrom and means rec air to at least one cylinder of the engine, eachcomprising a casing and two co-operating impellers, some of saidimpellers being located coaxially of said crank shaft, and some beingunbalanced and located eccentrically thereof and means for driving eachunbalanced impeller at the same speed as a cooperating balancedimpeller.

3. In combination with the cylinders and pistons of a two cycle engine,a crank shaft, separate piston rods between said shaft and the separatepistons, a plurality of blowers for delivering air under pressure to atleast one of said engine cylinders, each comprisin a casing,twoeccentrically arranged impe lers one of which is unbalanced located ineach casing and means for driving said impellers whereby unbalancedforces occasioned by their rotation counteract unbalanced forces of theengine.

In testimony whereof I have signed this specification.

(CllAllLlES LEQNARD ARMANI!) MAURHCE LEBLANC.

